PHOENIX — Reliever Ryan Cook's availability for opening day may not be as straightforward as the A's reliever would like.

A day after Cook, coming back from shoulder tightness, threw 20 pitches off a mound for the first time this spring and said he was more confident than ever that he'd be ready for opening day, manager Bob Melvin tapped on the brakes.

``We'll see where that one goes,'' Melvin said. ``He's still going to have to go through all the things the other guys had to do — multiple bullpens, throwing to hitters and then the games. So I don't know.

``Once we actually get him into the games, the timetable will be a little clear. As of right now, I still don't know.''

Typically the last thing a reliever has to do in the spring is pitch in back-to-back games. Because of the depth of the Oakland bullpen, Melvin might give Cook, the right-handed setup man in the eighth inning, a little room to maneuver.

``I think you could waive that,'' he said.

The other relievers typically will have pitched between eight and team times during the spring. Melvin is not sure what number would suffice to get Cook, who is 12-6 with a 2.30 ERA and an All-Star Game berth during his two seasons with the A's, on the roster for March 31's opener against the Indians in Oakland.

``You don't want to cut him short,'' he said. ``You don't want him speeding up to try to do things differently to try to get there on time. We'll be cautious with him. I don't see us speeding it up at this point.''